Epstein explains his decision

Football legend Bill Walsh used to say that coaches and executives should seek change after 10 years with the same team. The theory is that both the individual and the organization benefit from a change after so much time together. The executive gets rebirth and the energy that comes with a new challenge; the organization gets a fresh perspective, and the chance for true change that comes with new leadership. This idea resonated with me. Although I tried my best to fight it, I couldn’t escape the conclusion that both the Red Sox and I would benefit from a change sometime soon.